how we can find the output temperature of water all glass evacuated tube solar water heater in single tube for the given inlet temperature of water?
Hi, Yuvaraj, your question is not clearly understand.
However, a solar water heater is used to supply hot water for daily purposes in households, industries process work, paper mill etc. For this if you supply normal water say at atmospheric temperature to the SWH you can get your desired temperature depending on solar intensity, time of the day and definitely on the geographic position. In addition, what temperature do you want from your SWH also depends on design accordingly.
hi dear,
first of all you have to know the solar energy available at your selected location for solar water heater operation.
From the solar energy you can calculate the maximum energy out put from the collector using the simple calculation.
Q=solar radiation * collector area* collector efficiency
then you can calculate deltaT (temperature difference between inlet and outlet )
Q = m * Cp * (Tout - Tin)
this is simple way to estimate temperatures. in actual operation it may vary due to collector tilt, collector face direction, and wind speed.
The operational parameters and efficiency of a collector can be obtained from
www.spf.ch
Is the solar water heater working on thermosyphon system or forced flow. If forced flow, is the flow under laminar or turbulent conditions. Make use of the equations available for the relevant condition for flow in a single tube and estimate the heat transfer coefficient. On estimation of the h.t.c., you have equations available to determine the outlet temperature of the flowing liquid. The values can be arrived at through iterative process.
As mentioned in respected offered answers, you nee to know the solar intensity (W/m^2), then have the transmittivity of the glass surface, and the absorbtivity of the water coil and coil surface area with an effectivenss. Multiply the four terms results in the heat carried out by the flowing water. This amount is divided by the heat capacity (mwater x specific heat), then add this to the inlet water temperature to get the outlet temperature.
First of all you must know how much heat you can collect from the sun into the Surface.
After that how much heat you can transfer to the water at different water velocity.
This is depending of the design of the water flow channels (
- heat transfer coefficients and heat conduction in flanges e.t.c.
A way of presenting results is shown in the attachment.
iam doing project on all glass evacuated tube solar water heater iam unable to get some details regarding solar radiation if we give water at tem 300K as T in in a single evacuated tube how to find T out .
Hi dear,
You can get details of solar radiation from NASA SSE for any location worldwide. With out know solar radiation you can not know the collector outlet temperature unless you have experimental setup and measure temperature.
If collector efficiency chart is available, you need to put temperature difference and irradiation for finding abscissa value. Based on the efficiency curve, you can find the value of the efficiency available on the ordinate.
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